Electrical exchange.



Patented Dec. 5, 18991. A. E. KEITH a4. & c. J. EBICKSON.

ELECTRICAL EXCHANGE.

(Application filed Dec. 16, 1895.

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No. 638,249. Patented Dec. 5, I899. A. E. KEITH & J. & C. J. ERICKSON.ELECTRICAL EXCHA NGE.

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ELECTRICAL EXCHANGE.

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No. 638,249. Patented Dec; 5, I899. A. E. KEITH &. J. & c. .1. EBICKSON.ELECTRICAL EXCHANGE.

EAppIication filed Dec. 16, 1895.) (No Model.)

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WITNESS-Es: INVENTO S. M

nrrnn TATES PATEN FFICEt ALEXANDER E. KEITH, JOHN ERIOKSON, AND CHARLESJ. ERIOKSON, OF CHICAGO, ILLINOIS, ASSIGNORS TO THE STROWGER AUTOMATICTELE-' PHONE EXCHANGE, OF SAME PLACE.

ELECTRICAL EXCHANGE.

SPECIFICATION forming part of Letters Patent No. 638,249, dated December5, 1899. Application filed December 16, 1895. Serial. No. 572,831. (N0model.)

To all whom it may concern:

Be it known that we, ALEXANDER E. KEITH,

J OHN ERICKSON, and OHARLEs J. ERICKSON, citizens of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a new and useful Electrical Exchange, of which the following isa specification.

Our invention relates to electrical exchanges; and our object is tointroduce several novel features and modifications in the constructionof the system of electrical exchanges embodied in Letters Patent of theUnited States No. 540,168, dated May 28, 1895, to Alexander E.KeithrFrank A. Lund= quist, John Erickson, and Charles J. Erickson, andalso application for patent of the United States for electricalexchange, Serial No. 556,229, filed July 1'7, 1895, invented by Almon B.Strowger, Frank- A. Lundquist,

John Erickson, and Charles J. Erickson, our new improvements beingdescribed hereinafter and illustrated in the accompanying drawings, inwhich- Figure 1 is a front view, and Fig. 2 a side elevation, of anelectrical exchange in the suspended normal position, in which isembodied the greater part of our improvements. Figs. 3 and 3 aredetached portions of the elevation shown in Fig. 2,with several of theparts in a changed position to illustrate the manner of operating anautomatic cut-out for a secret system. Figs. 4, 4, and 4 show horizontalsections of a portion of several exchanges on broken line 1 2, Fig. 1,looking downwardly, and illustrate the curved position of thecontact-points and the manner of connecting the interconnecting wires ofseveral exchanges, together with the relative position of the mainswitch arms or wipers at the normal position and when in touch with thecontact-points. Figs. 5 and 5 illustrate the half-twist of theinterconnecting Wires at the point of connection with the contactpiecesand also show that the interconnecting wires are stripped of theinsulation where they attach to the contact-strip hooks. Fig.

6 shows, respectively, a front elevation and a plan of one of the curvedmetal strips which serve as end pieces for the attachment of rivets orbolts which pass through a group of contact-points comprising a numberof curved insulating-pieces, shown in elevation and plan view in Fig. 7.Fig. 8 is a plan view of oneof the curved insulating-pieces shown inFig. '7 as it appears when attached to the exchange, with thecontact-points in position, and one of the wipers for contacting thesame attached to its shaft and in the normal position. Figs. 8 and 8 arebroken detail views of the releasing mechanism, taken in two po sitions,and 8 is a detail view of the bent wire 48. Fig. 9 is a plan View of themain shaft with ratchets through which the same is operated mountedthereon, an auxiliary switch being also shown in position, together withthree wipers, these several points being shown in the initial position.Fig. 9 is an elevation the same as upper portion of Fig. 9, but with. anauxiliary switch-arm in the position it occupies after six step-by-stepr0- tary movements and after the main shaft has had the firstlongitudinal step-by-step movement. Fig. 9 is asimilar elevation asshown in Fig. 9, with the exception that the main shaft has had fivelongitudinal step-by-step movements upwardly and two step-by-step ro=tary movements in the direction indicated by arrow A, the auxiliaryswitch having had two rotary step-by-step movements on the shaft and inthe same direction, as indicated also by arrow A. Fig. 9 is across-section of the main shaft on line 3 4, Fig. 9, showing theauxiliary switch and one of the wiper-arms of the main switch in bottomelevation or when looking in the direction indicated by arrow B. Fig. 9is a horizontal section on line 5 6, Fig. 9 or Fig.

9 of the rotary ratchet-Wheel, with a plan of the auxiliary-switchcontact-point holder and contact-arm in touch with the secondcontactpoint. Fig. 10 is an elevation and a plan of the cylindricalratchet through which a longitudinal movement is imparted to the mainshaft, there beinga projecting strip at one side of this ratchet for apurpose which is explained hereinafter. Fig. 11 shows, respectively, anelevation and a plan of the ratchet through which a rotary movement isimparted not only to the main shaft but to the arm of the auxiliaryswitch. Fig. 12 shows, respectively, a front and side elevation and aplan of the holder,of insulating materiahinto which are secured theseveral contact points or pins of the auxiliary switch, which holder isfirmly secured to the main shaft and partakes of all its movements.Figs. 13, 13, and 13 are vertical sections of the top plate of the frameof the exchange and of the main shaft on broken line 7 7, Fig. 2,looking in the direction indicated by arrow 0, to illustrate the actionof a spring cut-out which is fully described hereinafter. Figs. 14, 14,15, and 15 are diagrammatic views of two complete telephone systems,withthe exchanges therefor,the same capable of being connected, the partsbeing shown in the normal position, and, in order to avoidcomplication,the telephone,we will suppose, is of the magneto varietyand may therefore be used forboth transmitter and receiver. Figs.16,16,17, 17 18, and 18", respectively, represent three interconnectedtelephone systems and the exchanges therefor, the telephone set in Fig.16 and the one in Fig. 18 being in speaking connnection through theexchange in Fig. 16.

The telephone set in Fig. 17 and the exchange therefor in Fig. 17 areshown connected to the exchanges in Figs. 16 and 18 to illustrate theaction of an automatic secret service cut-out which each exchange isprovided with and which effectually prevents two persons whosetelephones are connected being disturbed in conversation by a person atany other telephone of a given system.

Similar numerals indicate like parts throughout the several views.

In the drawings, 8 indicates the several parts comprising the frame ofthe exchange, to the upper part of which is pivotally mounted the shaft9, which is disposed vertically and is operated longitudinally upwardstep by step against gravity by means of a pawl 10, engagingin theteethof cylindrical ratchet 11, the pawl 10 being attached to the free end ofan arm 10, which is operated by virtue of electromagnet 12.

and pawl 14 engaging with ratchet-wheel 15, all of which mechanism,including the detents, is almost an exact duplicate of what is shown inapplication for patent Serial No. 556,229 and hereinbefore referred to,and therefore no particular description thereof is necessary. inventionand in the claims we shall refer to the shaft 9 and its connected partsas a connector, and the two magnets 12 and 13 will be designated asmotormagnets. The ratchet-wheel 15, however, in this instance is looselymounted upon shaft 9 and. is held in the initial position shown byhelical spring 15', which has one end attached to adownwardly-projecting arm 15 and the other end to the boss 17 of theauxiliary-switch contact-point holder 18, which boss is firmly securedto shaft 9. This spring holds the arm Shaft 9 is rotated step by .stepby virtue of magnet 13 through lever 14 In the further description ofour 15 normally in contact with a stop 19, projecting from thecontact-point holder 18.

There is a combined switch arm and coupler,

in the form of the arm 20, which is firmly secured to and projectslaterally from the lower end of the ratchet-wheel 15. Near the outer endof the arm 20 is a hole-20, Figs. 9 9 and 11, which is at a distancefrom the center of shaft 9 so that as the ratchet 15 is revolved step bystep against the tension of spring 15 the arm 20 is carried around andat the termination of each step the hole 20 registers with one of thecontact-points 21, which are seen red in the insulating-holder 18. Thereare ten contact-points 21 shown in Figs. 2, 9 and 12; but a greater orless number may be used, as may be necessary.

Shaft 9is provided with a series of wipers insulatingly secured thereto,and in this instance all project from the same side of shaft 9. Onlythree wipers, 22, 22, and 22", are shown, but more may be used in largecentral stations, as may be required. Each wiper is connectedindependently by a wire to someone of the contact-points 21, and each ofthe several wires has an insulating-covering, and for convenience thewires are formed into a cable, as shown in Figs. 1 and 2.

The several exchanges of any given system are each provided with one ormore groups, such as 24 24' 24", of contact-points 25, Figs. 1, 2, and8. Each contact-point is insulated from the other, and they are rangedin straight vertical rows, but in concave horizontal rows, as shown.Each group of contact-points is usually numbered 100 and securedbetween, plates of insulating material 25, Fig. 7, and

each group is secured upon vertical side rods 26 by means of the plates26, Fig. 6, as shown, there being one wiper for each group. The firstcontact-point of each group of the top or first series of groups isconnected by an interconnecting wire 27 with the first contact-point ofall the groups of that series, and the second contact-point is connectedby a wire 27 with the second contact-point of all the groups of thatseries, and wire 27'connects thethird contact-point, and so on, with allthe contact-points of each of the other series of groups, as shown inFigs. 4, 4 and 4 At the lower end of the side rod 26 is secured an arm28, to which is pivotedan arm 29, whose other end is pivoted to thelower end of a short piece of round rod 30, which projects upwardlywithin helical spring 31. The upper end of rod 30 is pointed and hasabearing in the center of lower end of the main shaft 9, which may turnthereon, but is held in contact therewith by the tension of spring 31,which has the lower end secured to rod 30 and the upper end to the bossshown on the lower end of shaft 9, this spring also serving to turnshaft 9 backwardly to the normal position after it has been revolvedforwardly by the action of the pawls hereinbefore described, the pin 32at the top end of shaft 9 serving as a stop by contacting the insulatedpin 33, which is attached to the exchange-frame 8.

Spring 34, at the lower end of the exchange, serves to carry part of theweight of shaft 9, and thus relieve the strain of pawl 10 in lifting theshaft step by step vertically.

Secured to ratchet 11 isa strip of metal 35, and insulatingly attachedto the side of the top of frame 8 at 36 is a spring 36,whose top end isadapted to contact strip 35 at any point of the upward longitudinalstep-by-step movement of ratchet 11. There is a detent 37, which servesto hold ratchet 15 in any desired operative position, and detent 37 issecured to one end of a pivotal shaft 38, and at the other end issecured a detent 39, which engages with the ratchet-cylinder 11, so thatin the act of release both detents are simultaneously lifted from theratchets.

At the top of the detent 39 is a laterallyprojecting pin 40,0finsulating material,whioh has a position, as shown in Figs. 13, 13", 13so that when the detents 37 and 39 are out of contact with the ratchetsby the rotation of the shaft 38 the pin 40 forces spring 36 out ofcontact with strip 35 on ratchet 11, and no current can pass from thespring into ratchet 11, shaft 9, and the frame 8 of the exchange. If,however, ratchet-wheel 15 is actuated one step forwardly, the spring 36is dropped into contact with strip 35 by the falling of detent 39 intoengagement with ratchet 11, as shown in Fig. 13 The shaft 38 is rotatedso as to throw the detents out of engagement with the ratchets by meansof an arm 37, which extends across the frame above a wire tailpiece 10",projecting from the pawl 10. The tailpiece is bent so as to form anincline which engages with the inner end of the pin 14",which projectsthrough the lever 14 and which is carried into the path of the tailpiecewhen the lever is drawn forward by the action of the magnet 13. If whilethe lever 14 is drawn forward the magnet 12 should be energized, so asto draw the arm 10 forward, and with it the pawl 10, the tailpiece 10would be forced into engagement with the pin 14, andthe inclined portionwould raise the end which is under the arm 37, and thereby rotate theshaft 38, thus throwing the detents out of engagement with the ratchetsupon the shaft 9. Now if the magnets 9 should be energized withoutdenergizing the magnet 12 the lever 14 will be forced back into itsnormal position and the outer end of the pin 14" will pass under theouter end of the arm 37, which is bent at an angle and is raised abovethe pin when the tailpiece is operated. While these parts are in thisposition, if the magnet 12 should be denergized the arm 10 and the pawl10 will resume their normal position; but the bent portion of the arm 37will engage with the pin 14" and be retained in that position, therebyholding the pawls 37 and 39 out of engagement with their respectiveratchets.

The cut-out or means by which the conversation between two persons ismade secret is shown in Figs. 1 and 2 and is constructed as follows:

At 41 and 42 are single-spool electromagnets whose coils are notdirectly connected; but the two spools are secured to the samecross-piece, and at 42 is an arm which is not only an armature formagnets 41 and 42, but the free end thereof projects forward to adistance sufficient to contact the two projections 43 and 44 near theend of a spring 45, whose opposite end is insulatingly attached to frame8 at 45. Projection 44 on spring 45 is a piece of insulating material;but projection 43 is integral with the spring, so that current may passfrom arm 42 into spring 45 when in the normal position, with arm 42 incontact with projection 43, Fig. 2; but no current can pass betweenthese two parts when the arm 42 is drawn in by virtue of electromagnets41 and 42 to the position shown in Fig. 3, where the end of arm 42 is incontact with the piece of insulation 44.

In Fig. 2 is shown a bent arm 46, projecting from the base which formsthe pivotal end of arm 14. The vertically-disposed free end of arm 46 isin contact with bent wire 48, which is in the form of a bell-crank, asseen in Fig. 8 and is pivoted to a block 49, Fig. 1, then extendingacross the front plate of frame 8,

and at the free end is covered with a piece of I insulating material 49.

Spring 45 extends from insulator 45 and passes over and rests upon theinsulated portion 49 of bent wire 48. At 51 is an insulated screwsecured to frame 8, and to this screw is attached a spring 52, and at 53is an arm projecting from the armature of magnet 13, the other end ofwhich arm is normally near, but not in contact with, spring 52; butshould magnet 13 become energized arm 53 Will contact spring 52 and bendit down, as is shown in Fig. 3, and at the same time the bent arm 46causes the insulated end 49 of bell-crank lever 48 to move spring 45into contact with a cross-spring 55, which has one end attached to theframe of the exchange by a piece of insulated material, Fig. 3, so thatif magnet 41 is energized the arm 42 is free to take the position shownin Fig. 3, when if magnet 41 continues to be energized until after thecurrent is out out from magnets 13 and 42 the spring 45 will drop, withthe free end of arm 42 in contact with the piece of insulation 44, inwhich position no current can pass between spring 45 and arm 42, whicharm is pivoted to and is in electrical connection with the frame andshaft9. Therefore any one making an attempt to cut into either of thelines of two already-connected telephones will automatically cut himselfout every time his main switch-arm contacts either of the twocontactpoints of the two connected exchanges, the course of the currentto accomplish this being described hereinafter.

The manner of attaching the interconnecting wires 27 to thecontact-point strips is i 44. w A

plainly shown in Figs. 4, 4, 4 5, and 5 the contact-point strips 25being provided with hooks at their rear ends, which engage with loopssuccessively formed at intervals along each of the interconnectingwires, the insulating-covering of these wires being cut at the point ofcontact, so that the bare wire may be soldered to the hooks to insure aperfect connection, the insulating material being slid back on the wirefrom the hook until after the soldering operation, when the insulationis again slid forward close up to the hooks, as shown. 1

In the construction of the shaft 9 and the several parts attachedthereto we do not claim any particular method of insulating the wipers22, &c.

The boss 17 is firmly secured to shaft 9 and serves as a stop bycontacting frame 8, and thus limiting the downward movement of theshaft.

As has been described, the ratchet-wheel 15 is loosely mounted on shaft9 to revolve and to slide a short distance longitudinally thereon; butwhen in the normal position it is held with the auxiliary switch-arm 20above the plane of the ends of the contact-points 21, and the lower endof the downwardly-projecting arm 15" and the lower end of boss 17 bothrest upon the frame 8, as is shown in Figs. 1, 2, and 9. If, however,the ratchet-wheel 15 is turned one step forward, it will turn upon shaft9 against the tension of spring 15 from the normal position shown in thebroken lines at F, Fig. 9 andin the solid lines, Fig. 9 to a positionwhen the hole 20is directly over the first contact-point 21 and shouldthe ratchetwheel be turned two steps the switch-arm 20 will have aposition with the hole 20 directly over the second contactpoint, asshown, when if from a thrust from pawl 10 against ratchet 11 shaft 9 islifted another step the second contact-point will be forced into thehole at the end of the switch-arm 20, and thus not only serves toestablish a circuit for an electric current from shaft 9 to the secondcontact-pin and thence by wire 23, Fig. 2, to wiper 22 and thence tosome one of the second group of contact-points in group 24,Figs. 1 and2, when the wiper is in contact there- 'with, but also serves as acoupler to cause shaft 9 to revolve step by step in unison with therevolution of ratchet-wheel 15 through the thrusts of pawl 14. It mustbe understood, therefore, that the auxiliary switcharm 20 must be set inthis instance first to connect with some one of the groups ofcontact-points 24 24, &c., before the shaft 9, together with the wipers22 22, &c., are per mitted to revolve or the shaft to movelongitudinally more than a single step. Each successive thrust of pawl10 lifts shaft 9 one step and carries each of the wipers 22, 22, and 22upward successively even with the ten hori zontal rows of contact-points25, and it is obvious that the several wipers may be lifted to registerwith any particular row of contactpoints and then by the successivethrusts of pawl 14 on the top of arm 14 be rotated to carry the freeends of the wipers into touch with any particular point 25 of the row.

The auxiliary switch embodied in the parts 18 20 and contact-points 21,with the wires connecting the points with the several wipers 22 22 22",&c., serves as a selector for connecting with some particular group ofone hundred-such as 24, 24, or 24", Figs. 1 and 2. In operation tofollow the course of the successive electric currents in makingconnection between two telephone-substations through theexchange-machines at the central station we will suppose that onetelephone set at a substation is represented by Fig. 14 and theexchange-machine directly connected thereto by two line-wires is Fig. 14and that the number of this telephone is 367. We will also suppose thatthe distant substation to be called is No. 295 and is rep resented bythe telephone set in Fig. 15 and its exchange-machine is Fig. 15, andthat not only these two telephone sets, but also the exchanges thereof,are at the normal position, as shown, and that the successive currentsof electricity are controlled at the central station in eachexchange-machine by means of three ordinary signal-keys at eachsubstation, these keys beingtoperated on the decimal system, andtherefore are denominated units, tens, and hundreds keys and are heredesignated by the letters H, T, and U. To call No. 295, the H orhundreds key is pressed twice in succession, causing two distinctelectrical impulses to pass from the main batteryD at the centralstation over battery-wire 56 to wire 57, Fig. 14, to the single-spoolmagnet 42, then by wire 58 to magnet 13, then by wire 59 to wire 61, tokey H, and to ground. (It will be noted that the first time thehundreds-key is pressed the magnet 13 is energized and the arm 14 isdrawn forward, so as to carry the pin 14 from under the end of the arm37, which permits the spring 38 to rock the shaft 38, and the detents 37and 39 are both permitted to drop upon their respective ratchets 15 and11,

which permits spring 36 to contact metal strip 35 at the side ofratchet-wheel 11, so that current may pass between spring 36 and shaft9.) Next press the T or tens key nine times in succession, causing nineelectrical impulses to pass from battery D through battery-wire 56 tomagnet 12, thence by wire 62 to spring 36, contact-strip 35 and shaft 9to pin 32, thence to insulated pin 33, then by wire 63 to wire 64, thenwire 65 to the key T or tens-key to ground. that when the tens-key ispressed the first time the shaft 9 is lifted longitudinally one step,which causes the auxiliary switch-arm to contact one of the pins 21 ofthe auxiliary switch, and thus make both an electrical and (It will benoted lifted nine steps, when each of the wipers 22, 22, and 22" is evenwith the ninth row, counting from the bottom row, of contact-points 25in each group.) Next press the U or units key five times in succession,causing five electrical impulses to pass from battery D through wire 56,then wire 57 to one-spool magnet 42, then by wire 58 to magnet 13 andwire 59 to wire and 61 to the U or units key to ground. (It will finallybe noted that the first time this units-key is pressed shaft 9 isrotated one step forwardly, which separates strip 35 from spring 36,Fig. 13 and also separates pin 32 from insulated pin 33, Fig. 16, and itwill be impossible to pass a current through the magnet 12, and therebyany injury to the contact-points or wipers by the longitudinal movementsof the shaft after it has been rotated one or more steps will beprevented.) Every time the U or units key is pressed arm 53 of thearmature of magnet 13 contacts insulated spring 52, which causes anelectric current to pass from the small battery E, Fig. 14, whichcontrols the releasing mechanism hereinbefore referred to, through wire67 to one-spool magnet 41, thence by wire 68 to spring 52, thencethrough arm 53 and base 8, to which it is pivoted, to shaft 9 and to arm20 of the auxiliary switch, which arm is" in contact with the secondcontact-pin thereof, as shown in Fig. 9 thence by wire 23 to wiper 22'to contact-point No. 295 of group 24, Figs. 1 and 2, thence by aninterconnecting wire 27 to connecting-wire 69 of exchange-machine,

Fig. 15 or Fig. 18, as the case may be, thenby wire 63 (of this exchangeNo. 295) to and through wire 64 to telephone-lever then wire 74 to thegenerator then wire 7 6 to the ringer-magnets 77 then wire 59 to magnet13, then wire 58 to magnet 42, thence through wire 57 to battery-wire 56and wire 73 to small battery E, Fig. 14, which completes this circuitand energizes the magnet 41. This electric current last described inpassing over this circuit must pass either through the ringing-magnetsof the hell or the telephone or in passing over the lines of twosubstations connected together the current is divided and passes overboth circuits. Usually the bell-magnets are of high resistancesay onethousand ohms-and the telephone is of low resistance-say one hundredohms. This current from small battery E in passing over this circuit, asdescribed, if it passes through the high-resistance bell-ringer magnetsis not of sufficient strength to hold the armature or arm 42 againstmagnet 41 after magnets 13 and 42 are denergized, thus permitting thearm 42 to fall back into normal position and complete thetalking-circuit with any substation with which connection has been made.The two telephones Nos. 367 and 295 are now in connection, and theringing-circuit is from generator 75, Fig. 14, through wire 76,ringermagnets 77, wire 59, and magnet 13, then wire 58, magnet 42, andthrough wires 57, 56, and 57, Fig. 15, to magnet 42", then wire 58 tomagnet 13, wire 59 to ringer-magnet 77, Fig. 15, then by wire 76,generator 75, wire 74, telephone-lever 70, wire 64, wire 63, thenconnecting-wire 69 to the interconnectingwire 27 A to wiper 22 ofexchangemachine, Fig. 14, as shown in proper position in Fig. 16, thenthrough wire 23, contact-point No. 2 of the auxiliary switch, and thenthe switch-arm 20 thereof, shaft 9, base 8, and arm 42, spring 45, wires63 and 64, telephone-lever 70 of telephone setNo. 367, Fig. 14, wire 74,and to generator 75, which completes the ringing-circuit. The telephonesNos. 367 and 295 are now removed from their levers 70 and 70, when thetalking-circuit is established, the mechanism of the exchange-machine inFig. 16 being shown in the operated position connecting the twotelephones. This talking-circuit is the same as the ringing-circuit,with the exception of the ringers and the generators therefor, which arecut out and the telephone switched in. While these two telephones areoff their respective levers, should any one attempt to make a connectionwith either of the already-connected telephonesay a person at telephone118, Fig. 17*, should attempt to call a person at telephone 295, Fig. 18and presses the H or hundreds key twice and the T or tens key nine timesand the U or units key five times-every time he presses the units-key hecloses the contact between arm 53 and spring 52, the electric pulsationsfrom small battery E in passing over the circuit, which includes thelow-resistance telephone 295, being of sufficient strength to hold thearm 42 against magnet 41 and permit the insulated contact 44 of spring45 to fall back of and contact the free end of arm 42, whereby thecircuit is broken, in which event it is obvious that the bells ofneither one of the connected parties can be sounded nor theirconversations be heard.

In each of the diagrammatic views is a separate small battery E, E, or Efor each exchange-machine in order to show as small a number of exchangeinterconnecting-wires as possible; but it must be understood in practicethat one small battery, such as E, of less power than battery D servesfor several or the whole number of exchange-machines at the centralstation.

To cause the several operative parts to return to the normal positionafter a conversation, magnet 13 is first electrically energized and thecurrent is not cut out until after magnet 12 is energized, which,through the pin 14" and tailpiece 10", causes the detents and pawls tosuccessively lift from their respective ratchets, when shaft 9 is firstrevolved backwardly and then slides downwardly to the position shown inFigs. 1 and 2. In the downward movement of the shaft the auxiliaryswitch is caused to resume the released or normal position by the lowerend of the downwardly-projecting arm 15 contacting the frame 8 beforethe shaft 9 has reached its lowest position, which causes the boss 17and the contact-point holder 18, which are secured to the shaft, and bythe downward motion thereof to withdraw any contactpoint 21 which may beengaged with hole 20' in the auxiliary switch -arm 20, when theresiliency of spring 15 causes a backward movement of theratcl'iet-wheel 15 to the normal position, with projection 15 restingagainst projection 19 of the contact point holder 18, Fig. 9

It will be noted that since the boss 17 and the contactpoint holder 18are secured to shaft 9 these two parts are first carried around to thenormal position shown in Figs. 1 and 2 with the first backwardrevolution of the shaft and that the ratchet-wheel 15 is revolved on theshaft, together with the auxiliaryswitch-arm 20, always after the shafthas reached its lowest position. The shaft 9 being mounted to operatelongitudinally in a vertical direction, it is obvious that most of theweight thereof may be counter balanced by the upward pull of spring 34,and since a step-bearingis provided at the lower end upon the pointedupper end of rod 30, which is disposed within spring 31, friction in thebearing thereof is reduced to avery small amount,even when the shaft ismade much longer than is shown in the drawings, to receive an additionalnumber of switch-arms, when an ad tional number of groups ofcontact-points are necessary in large exchanges.

Ve claim as our invention 1. In an electrical exchange, the combination,with a series of contact-points arranged in groups, of a switch providedwith an arm for each group, a series of contact-points mountedindependently of the switch but in electrical communication with thedifferent arms, and a selector or auxiliary switch-arm rotatably andlongitudinally movably mounted upon the first-mentioned switch, andmeans for establishing electrical communication with either of saidgroups through said selector, substantially as set forth.

2. In an electrical exchange, the combination, with a series ofcontact-points arranged in groups, of a shaft provided with an arm foreach group, a series of contact-points in electrical communication withsaid arms, a selector or auxiliary switch rotatably and 1ongitudinallymounted upon said shaft, the contact end of which is normally out ofengagement with said second-mentioned contactpoints, and means forrotating the selector, and means for moving theshaft longitudinally,whereby contact is made between the se lector and one of the points,only after the selector has been moved one or more steps from its normalposition, substantially as set forth.

3. In an electrical exchange havinga shaft with a plurality ofswitch-arms insulatingly attached thereto and each adapted to contactany one of some group of contact-points by virtue of either a rotary ora combined rotary and longitudinal movement of the shaft, an auxiliaryswitch mounted on the shaft and consisting of a series of insulatedcontactpoints each having electrical connection with some one of theswitch-arms, a ratchet-wheel loosely mounted upon the shaft to revolveor slide longitudinally thereon and having an arm attached thereto whichforms a terminal in electrical connection with a substation, the firstrotary step-by-step movements of the ratchet-wheel adapted to cause thearm attached thereto to register with some one of the said insulatedcontact-points without turning the shaft, butthe first longitudinalmovement of the shaft couples the arm with the contactpoint with whichit is in register, whereby any subsequent stepby-step rotary movementsof the ratchet-wheel cause the shaft to revolve in unison therewith forthe purpose stated.

4. In an electrical exchange, the combination, with contact-points, of alongitudinallymovable shaft, a selector thereon, a lock for the shaft,said selector and lock being in such relation to each other and to theshaft, that when the shaft is moved the first step longitudinallyit willengage with the selector and will become disengaged from the lock,substantially as set forth.

5. In an electrical exchange, the combination, with contact-points, of alongitudinallymovable shaft provided with a series of pins arrangedparallel therewith, a platform, a lock, and a selector provided with twoarms, one of which normallyrests upon the platform and the other one isadapted to be placed in engagement with the pins, said parts being insuch relation to each other that when the shaft is moved the first steplongitudinally it will simultaneously cause the pins to engage with oneof the arms of the selector and to become disengaged from the lock, andwhen it is moved the last step in the opposite direction it will besimultaneously disengaged from the lock and the pins will be disengagedfrom the arm of the selector, substantially as set forth.

6. In an electrical exchange havinga switch or connector, of anauxiliary switch or selector, motor-magnets for operating the same, acircuit for each magnet, two single-spool electromagnets, one of whichis in the circuit of one of the motor-magnets, a separate circuit forthe other spool, a cross-piece and an armature common to both of saidsingle-spool magnets, the armature being adapted to lock the switch,substantially as set forth.

7. In an electrical exchange, the combination, with a series of linesfrom distant stations, of a series of connectors at the exchange, onefor each line, motor-magnets for each connector, a cut-out for each linebetween the connector and the distant station, an electrical circuit forthe cut-out including the connector and the cut-out, and means forautomatically passing a current of electricity through the cut-outcircuit to disconnect its connector from either of two connected lines,substantially as set forth.

8. In an electrical exchange, the combination, with a support, of ashaft journaled vertically therein and provided with contactarms, ofaspring-actuated vertically-movable step at the bottom of the shaft,means for moving the shaft upwardly step by step and means for releasingthe same and permitting the shaft to automatically resume its normalposition, substantially as set forth.

9. In an electrical exchange, the combination, with a support, of ashaft journaled therein and provided with contact-arms, ofcontact-points, an arm pivotally secured at the lower portion of thesupport, a rod in the arm, the upper end of which acts as a step for theshaft, a spring connected with the arm for partially counteracting theweight of the shaft, and means for moving the shaft upwardly step bystep, and means for releasing the same and permitting the shaft toresume its normal position, substantially as set forth.

10. In an electrical exchange, the combination, with supports, of ashaft journaled therein provided with contact-arms, contactpoints, anarm pivotally secured at the lower end of the support, a rod in the arm,the up per end of which acts as a step for the shaft, a spring securedto the arm and to the lower end of the shaft and surrounding the rod andshaft, and means for moving the shaft upward step by step, and means forreleasing the same and permitting it to automatically resume its normalposition, substantially as set forth.

In testimony that we claim the foregoing we have hereunto set our hands,this 19th day of August, 1895, in the presence of witnesses.

ALEXANDER E. KEITH. JOHN ERIGKSON. CHARLES J. ERIOKSON.

Witnesses:

JOSEPH HARRIS, OSCAR SNELL.

